Semiconductor package is the process in which a semiconductor die is encapsulated for protection and to provide ease of handling and usage. Packaged semiconductor dies can be handled at high speed by automatic machines for solder mounting upon the system boards. Solder is applied through a heating process forming electrical connections between system boards and contacts on the semiconductor dies. System boards provide wiring to interconnect electronic components and semiconductor dies. Semiconductor dies are used within electronic systems having many semiconductor dies soldered upon one or more system boards. Common examples of electronic systems are computers, cell phones and audio-video systems.
Common techniques for enclosing a semiconductor die include encapsulation and direct attachment methods. In both of these methods the semiconductor die, which is a small rectangular semiconductor die cut from a larger semiconductor wafer is covered with a polymer to seal and protect the semiconductor die. The polymer prevents the entry of water and other contaminants, which can cause problems during the various manufacturing processes.
The encapsulation process seals the semiconductor die within a polymer block and may include a set of exposed contacts connected to the semiconductor die with wires bonded to the semiconductor die and the exposed contacts. The direct attachment process provides an unpackaged semiconductor die adhered directly upon a system board, and provides wires bonded to the semiconductor die and the system board, followed by a complete covering of the semiconductor die and wiring with a sealing polymer.
Packaged semiconductors control and switch electrical signals and are seldom 100% efficient, packaged semiconductors therefore have losses that result in heating of the semiconductor die. Removal of heat from the semiconductor package prevents semiconductor overheating. High internal heat also causes stress cracks when dissimilar materials expand and contract at different rates with temperature. Modern electronic systems operate at ever faster speeds. Faster speeds lead to faster switching of signals, which leads to faster generation of losses and thus increased heat. Providing a means for spreading heat or providing a path for rapid heat flow within semiconductor packages and beyond has been a long sought need.
Modern electronic systems demand continued decreases in size. The volumetric size of systems is dependent not only on the area of the semiconductor package, but also on the thickness of the semiconductor package. Using thin semiconductor packages allows smaller electronic systems to be built. Current trends place a premium on semiconductor packages that can incorporate multiple semiconductor dies in stacks or stacks of packages.
One proposed solution involves providing a heat sink or metal slug attached to the semiconductor package to help remove the heat. Unfortunately, this additional element adds to the package thickness, and prevents stacking of multiple packages.
In most ball grid array package based lamination substrates, signal traces are created on a substrate made from BT-resin base, then solder balls on the bottom of the substrate are used to connect signal trace and board, and encapsulation material protects the chip and gold wire. But, in this package type, most of the junction generated heat can escape through the package top surface and board. However, the thermal path from the junction to the board is not good, because only the older balls are connected from the package to the board. To improve the thermal performance of the package, the thermal path toward the board has to be elevated.
Another proposed solution involves mounting the semiconductor die within a metal interior surface housing having sidewalls and flanges for retention. Unfortunately, this creates the need to use longer bond wires. Additionally, added vertical stress is created by the metal sidewalls of the housing.
Thus, a thinner package with high thermal dissipation is really required. In view of existing semiconductor packages it is increasingly critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.